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Message-Id: <1521755378.3848.295.camel@linux.vnet.ibm.com>
Date: Thu, 22 Mar 2018 17:49:38 -0400
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
linux-integrity@...r.kernel.org
Cc: linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
linux-crypto@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
David Howells <dhowells@...hat.com>,
David Woodhouse <dwmw2@...radead.org>,
Jessica Yu <jeyu@...nel.org>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
"AKASHI, Takahiro" <takahiro.akashi@...aro.org>
Subject: Re: [PATCH v6 02/12] PKCS#7: Introduce pkcs7_get_message_sig() and
verify_pkcs7_message_sig()
Hi Thiago,
On Fri, 2018-03-16 at 17:38 -0300, Thiago Jung Bauermann wrote:
> IMA will need to know the key that signed a given PKCS#7 message, so add
> pkcs7_get_message_sig().
>
> It will also need to verify an already parsed PKCS#7 message. For this
> purpose, add verify_pkcs7_message_sig() which takes a struct pkcs7_message
> for verification instead of the raw bytes that verify_pkcs7_signature()
> takes.
The title "PKCS#7: refactor verify_pkcs7_signature()" might be more
appropriate. The patch description would then explain why it needs to
be refactored. In this case, verify_pkcs7_signature() verifies the
signature using keys on the builtin and secondary keyrings. IMA-
appraisal needs to verify the signature using keys on its keyring.
The patch itself looks good!
Reviewed-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
> Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
> Cc: David Howells <dhowells@...hat.com>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: "David S. Miller" <davem@...emloft.net>
> ---
> certs/system_keyring.c | 61 ++++++++++++++++++++++++++---------
> crypto/asymmetric_keys/pkcs7_parser.c | 16 +++++++++
> include/crypto/pkcs7.h | 2 ++
> include/linux/verification.h | 10 ++++++
> 4 files changed, 73 insertions(+), 16 deletions(-)
>
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 6251d1b27f0c..7ddc8b7a3062 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -190,33 +190,27 @@ late_initcall(load_system_certificate_list);
> #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
>
> /**
> - * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
> + * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data.
> * @data: The data to be verified (NULL if expecting internal data).
> * @len: Size of @data.
> - * @raw_pkcs7: The PKCS#7 message that is the signature.
> - * @pkcs7_len: The size of @raw_pkcs7.
> + * @pkcs7: The PKCS#7 message that is the signature.
> * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
> * (void *)1UL for all trusted keys).
> * @usage: The use to which the key is being put.
> * @view_content: Callback to gain access to content.
> * @ctx: Context for callback.
> */
> -int verify_pkcs7_signature(const void *data, size_t len,
> - const void *raw_pkcs7, size_t pkcs7_len,
> - struct key *trusted_keys,
> - enum key_being_used_for usage,
> - int (*view_content)(void *ctx,
> - const void *data, size_t len,
> - size_t asn1hdrlen),
> - void *ctx)
> +int verify_pkcs7_message_sig(const void *data, size_t len,
> + struct pkcs7_message *pkcs7,
> + struct key *trusted_keys,
> + enum key_being_used_for usage,
> + int (*view_content)(void *ctx,
> + const void *data, size_t len,
> + size_t asn1hdrlen),
> + void *ctx)
> {
> - struct pkcs7_message *pkcs7;
> int ret;
>
> - pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
> - if (IS_ERR(pkcs7))
> - return PTR_ERR(pkcs7);
> -
> /* The data should be detached - so we need to supply it. */
> if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
> pr_err("PKCS#7 signature with non-detached data\n");
> @@ -258,6 +252,41 @@ int verify_pkcs7_signature(const void *data, size_t len,
> }
>
> error:
> + pr_devel("<==%s() = %d\n", __func__, ret);
> + return ret;
> +}
> +
> +/**
> + * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
> + * @data: The data to be verified (NULL if expecting internal data).
> + * @len: Size of @data.
> + * @raw_pkcs7: The PKCS#7 message that is the signature.
> + * @pkcs7_len: The size of @raw_pkcs7.
> + * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
> + * (void *)1UL for all trusted keys).
> + * @usage: The use to which the key is being put.
> + * @view_content: Callback to gain access to content.
> + * @ctx: Context for callback.
> + */
> +int verify_pkcs7_signature(const void *data, size_t len,
> + const void *raw_pkcs7, size_t pkcs7_len,
> + struct key *trusted_keys,
> + enum key_being_used_for usage,
> + int (*view_content)(void *ctx,
> + const void *data, size_t len,
> + size_t asn1hdrlen),
> + void *ctx)
> +{
> + struct pkcs7_message *pkcs7;
> + int ret;
> +
> + pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
> + if (IS_ERR(pkcs7))
> + return PTR_ERR(pkcs7);
> +
> + ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage,
> + view_content, ctx);
> +
> pkcs7_free_message(pkcs7);
> pr_devel("<==%s() = %d\n", __func__, ret);
> return ret;
> diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
> index a6dcaa659aa8..456b803972b5 100644
> --- a/crypto/asymmetric_keys/pkcs7_parser.c
> +++ b/crypto/asymmetric_keys/pkcs7_parser.c
> @@ -683,3 +683,19 @@ int pkcs7_note_signed_info(void *context, size_t hdrlen,
> return -ENOMEM;
> return 0;
> }
> +
> +/**
> + * pkcs7_get_message_sig - get signature in @pkcs7
> + */
> +const struct public_key_signature *pkcs7_get_message_sig(
> + const struct pkcs7_message *pkcs7)
> +{
> + /*
> + * This function doesn't support messages with more than one signature,
> + * so don't return anything in that case.
> + */
> + if (pkcs7->signed_infos == NULL || pkcs7->signed_infos->next != NULL)
> + return NULL;
> +
> + return pkcs7->signed_infos->sig;
> +}
> diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
> index 583f199400a3..6f51d0cb6d12 100644
> --- a/include/crypto/pkcs7.h
> +++ b/include/crypto/pkcs7.h
> @@ -28,6 +28,8 @@ extern void pkcs7_free_message(struct pkcs7_message *pkcs7);
> extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
> const void **_data, size_t *_datalen,
> size_t *_headerlen);
> +extern const struct public_key_signature *pkcs7_get_message_sig(
> + const struct pkcs7_message *pkcs7);
>
> /*
> * pkcs7_trust.c
> diff --git a/include/linux/verification.h b/include/linux/verification.h
> index a10549a6c7cd..f04dac2728ec 100644
> --- a/include/linux/verification.h
> +++ b/include/linux/verification.h
> @@ -29,6 +29,7 @@ extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR];
> #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
>
> struct key;
> +struct pkcs7_message;
>
> extern int verify_pkcs7_signature(const void *data, size_t len,
> const void *raw_pkcs7, size_t pkcs7_len,
> @@ -38,6 +39,15 @@ extern int verify_pkcs7_signature(const void *data, size_t len,
> const void *data, size_t len,
> size_t asn1hdrlen),
> void *ctx);
> +extern int verify_pkcs7_message_sig(const void *data, size_t len,
> + struct pkcs7_message *pkcs7,
> + struct key *trusted_keys,
> + enum key_being_used_for usage,
> + int (*view_content)(void *ctx,
> + const void *data,
> + size_t len,
> + size_t asn1hdrlen),
> + void *ctx);
>
> #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
> extern int verify_pefile_signature(const void *pebuf, unsigned pelen,
>
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